The methods and systems of the present invention are directed to the modification and improvement of transmissions for automotive vehicles, more commonly referred to as "factory installed" transmissions, installed in an automotive vehicle by an original automobile manufacturer. The present invention is more particularly directed to "factory installed" transmissions identified as Model Nos. 4L60E and 4T60E, installed in vehicles manufactured by General Motors Corporation, Detroit, Mich., and Model No. CD-4E installed in vehicles manufactured by The Ford Motor Company of Dearborn, Mich. The components and operation of these three "factory installed" automotive transmissions are disclosed in the following publications, each of which is expressly incorporated by reference into the present patent application: Hydra-Matic 4T60-E Technician's Guide, General Motors Corporation, Hydra-Matic Division, Second Edition, January 1991; Hydra-Matic 4L60-E Technician's Guide, General Motors Corporation, Power Train Division, 1992; and CD4E Automatic Transaxle Theory/Operation Reference Manual, Ford Motor Company, 1993.
The present inventor owns the following United States Patents, each of which is also expressly incorporated by reference into the present patent application: U.S. Pat. No. 4,449,426, issued May 22, 1984; U.S. Pat. No. 4,711,140, issued Dec. 8, 1987; U.S. Pat. No. 4,790,938, issued Dec. 13, 1988; U.S. Pat. No. 5,253,549, issued Oct. 19, 1993; U.S. Pat. No. 5,540,628, issued Jul. 30, 1996; U.S. Pat. No. 5,624,342, issued Apr. 29, 1997; U.S. Pat. No. 5,730,685, issued Mar. 24, 1998; U.S. Pat. No. 5,743,823, issued Apr. 28, 1998; U.S. Pat. No. 5,768,953, issued Jun. 23, 1998; U.S. Pat. No. 5,820,507, issued Oct. 7, 1998; and U.S. Pat. No. 5,967,928, issued Oct. 19, 1999.
In the factory installed CD-4E transmission, Applicant has recognized that the arrangement of the main regulator valve, and the flow of fluid therethrough, can result in unregulated pressure applied to the valve resulting in an increase in line pressure exceeding the design limits. The excess pressure causes the valve to move in a direction which impedes fluid flow to the converter and cooler, resulting in potential damage to components of the system as a result of the overpressure, and overheating of the converter as a result of the disruption of the fluid flow to the cooler.
The factory installed 4T60-E transmission includes an isolator valve having a relative small length/diameter ratio resulting in potential misalignment of the valve which accelerates wear in the bore in which the valve reciprocates. The worn bore is likely to cause fluid leaks, adversely affecting operation of the valve and the overall hydraulic circuit of the transmission.
The factory installed 4L60-E transmission also has an isolator valve which has a relatively small length/diameter ratio. As discussed above with respect to the 4T60-E transmission, this isolator valve tends to tip, thereby accelerating wear of the bore in which it reciprocates, causing fluid leaks which adversely affect the operation of the hydraulic circuitry of the factory installed transmission.
It is the primary object of the present invention to overcome the known disadvantages of the CD-4E, 4T60-E and 4L60-E automotive transmissions by modifying components and/or the arrangement of hydraulic circuitry in the respective factory installed transmissions. Other objects and advantages of the present invention will become apparent to those skilled in the art from the following discussion.